1. Field of the Invention
The present invention relates to a hypoid reducing device having an improved coupling arrangement for a hypoid gear set and a motor. The hypoid gear set has a hypoid pinion shaft having a hypoid pinion at a tip end as an input shaft. The motor provides the hypoid pinion shaft with rotation driving force.
2. Description of the Related Art
Generally, in the manufacture of a geared motor, a series of reducers and a series of motors are separately manufactured, so that appropriate combinations can be selected. Therefore, a variety of general-purpose motors can be selected and combined with a specific reducer.
In the manufacture of a hypoid geared motor having a hypoid gear set with hypoid gears, a hypoid pinion must be formed at a tip end of the input shaft of the reducer, and the hypoid pinion must be provided in a gear case in the manner of a cantilever. Therefore, the hypoid pinion is often directly cut into the output shaft of the motor. In other words, the motor shaft could be exclusive, and the number of combinations available for the motors and reducers is limited. Therefore, a variety of general-purpose motors cannot be used.
Conventional hypoid geared motors have allowed the reducer and the motor to be independent and separate, so that combinations for reducers and motors can be more flexible.
FIG. 3 is a sectional view showing an arrangement of a hypoid gear set 100 and a motor 200 developed to form such a geared motor, and such an arrangement is, for example, disclosed by Japanese Patent Laid-Open Publication No. 2000-228847.
In the hypoid gear set 100 in FIG. 3, there are a hypoid pinion shaft 111, intermediate shafts 112A and 112B, and an output shaft 113. A hypoid pinion 114 is formed at the tip end of the hypoid pinion shaft 111, and a hypoid gear 115 to engage with the hypoid pinion 114 is provided at the intermediate shaft 112A.
When the hypoid pinion 114 engages the hypoid gear 115, the rotation direction of the motor shaft is changed at right angles.
A gear case 119 includes a main body case portion 119A, a coupling case portion 119B, and a pre-stage case portion 119C. The hypoid pinion shaft 111 is rotatably supported by two bearings 118A and 118B separated from each other in the axial direction over the coupling case portion 119B and the pre-stage case portion 119C.
The base end side of the hypoid pinion shaft 111 is hollow, and the motor shaft 201 of a motor 200 is inserted into the hollow space on the base end side. Bolts 204, 205, and 206 are used to couple the flange portion 202 of the motor 200 and the pre-stage case portion 119C, the pre-stage case portion 119C and the coupling case portion 119B, and the coupling case portion 119B and the main body case portion 119A, respectively.
The hollow hypoid pinion shaft 111 having the hypoid pinion 114 at its tip end is rotatably provided independently of the main body case portion 119A of the gear case 119 and the flange portion 202 of the motor 200, so that the hypoid gear set (100) as shown can be combined with various kinds of motors (200).
When the geared motor as described above is used, however, the hypoid pinion at the tip of the input shaft must frequently be changed. For example in the United States of America, there are set standards for motors and flanges. In general the motors and flanges according to these standards are not produced in Japan. Therefore, it is often the case that the geared motors as shown must locally be procured when they are used in the United States. In this case, the tip end of the hypoid pinion shaft must be adapted to such a locally procured motor.
The hypoid pinion must be worked using a special kind of working machine that is not normally available to any factories, and therefore cannot easily be worked to cope with different standards for the motor or flange. This increases both the working cost and manufacturing time.